/*
 * mppe.h - Definitions for MPPE
 *
 * Copyright (c) 2008 Paul Mackerras. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 4. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Paul Mackerras
 *     <paulus@samba.org>".
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT && MPPE_SUPPORT /* don't build if not configured for use in lwipopts.h */

#ifndef MPPE_H
#define MPPE_H

#include "netif/ppp/pppcrypt.h"

#ifdef __cplusplus
extern "C" {
#endif

#define MPPE_PAD 4          /* MPPE growth per frame */
#define MPPE_MAX_KEY_LEN 16 /* largest key length (128-bit) */

/* option bits for ccp_options.mppe */
#define MPPE_OPT_40 0x01       /* 40 bit */
#define MPPE_OPT_128 0x02      /* 128 bit */
#define MPPE_OPT_STATEFUL 0x04 /* stateful mode */
/* unsupported opts */
#define MPPE_OPT_56 0x08   /* 56 bit */
#define MPPE_OPT_MPPC 0x10 /* MPPC compression */
#define MPPE_OPT_D 0x20    /* Unknown */
#define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56 | MPPE_OPT_MPPC | MPPE_OPT_D)
#define MPPE_OPT_UNKNOWN 0x40 /* Bits !defined in RFC 3078 were set */

/*
 * This is not nice ... the alternative is a bitfield struct though.
 * And unfortunately, we cannot share the same bits for the option
 * names above since C and H are the same bit.  We could do a u_int32
 * but then we have to do a lwip_htonl() all the time and/or we still need
 * to know which octet is which.
 */
#define MPPE_C_BIT 0x01 /* MPPC */
#define MPPE_D_BIT 0x10 /* Obsolete, usage unknown */
#define MPPE_L_BIT 0x20 /* 40-bit */
#define MPPE_S_BIT 0x40 /* 128-bit */
#define MPPE_M_BIT 0x80 /* 56-bit, not supported */
#define MPPE_H_BIT 0x01 /* Stateless (in a different byte) */

/* Does not include H bit; used for least significant octet only. */
#define MPPE_ALL_BITS (MPPE_D_BIT | MPPE_L_BIT | MPPE_S_BIT | MPPE_M_BIT | MPPE_H_BIT)

/* Build a CI from mppe opts (see RFC 3078) */
#define MPPE_OPTS_TO_CI(opts, ci)                                                                  \
	do {                                                                                           \
		u_char *ptr = ci; /* u_char[4] */                                                          \
                                                                                                   \
		/* H bit */                                                                                \
		if (opts & MPPE_OPT_STATEFUL)                                                              \
			*ptr++ = 0x0;                                                                          \
		else                                                                                       \
			*ptr++ = MPPE_H_BIT;                                                                   \
		*ptr++ = 0;                                                                                \
		*ptr++ = 0;                                                                                \
                                                                                                   \
		/* S,L bits */                                                                             \
		*ptr = 0;                                                                                  \
		if (opts & MPPE_OPT_128)                                                                   \
			*ptr |= MPPE_S_BIT;                                                                    \
		if (opts & MPPE_OPT_40)                                                                    \
			*ptr |= MPPE_L_BIT;                                                                    \
		/* M,D,C bits not supported */                                                             \
	} while (/* CONSTCOND */ 0)

/* The reverse of the above */
#define MPPE_CI_TO_OPTS(ci, opts)                                                                  \
	do {                                                                                           \
		const u_char *ptr = ci; /* u_char[4] */                                                    \
                                                                                                   \
		opts = 0;                                                                                  \
                                                                                                   \
		/* H bit */                                                                                \
		if (!(ptr[0] & MPPE_H_BIT))                                                                \
			opts |= MPPE_OPT_STATEFUL;                                                             \
                                                                                                   \
		/* S,L bits */                                                                             \
		if (ptr[3] & MPPE_S_BIT)                                                                   \
			opts |= MPPE_OPT_128;                                                                  \
		if (ptr[3] & MPPE_L_BIT)                                                                   \
			opts |= MPPE_OPT_40;                                                                   \
                                                                                                   \
		/* M,D,C bits */                                                                           \
		if (ptr[3] & MPPE_M_BIT)                                                                   \
			opts |= MPPE_OPT_56;                                                                   \
		if (ptr[3] & MPPE_D_BIT)                                                                   \
			opts |= MPPE_OPT_D;                                                                    \
		if (ptr[3] & MPPE_C_BIT)                                                                   \
			opts |= MPPE_OPT_MPPC;                                                                 \
                                                                                                   \
		/* Other bits */                                                                           \
		if (ptr[0] & ~MPPE_H_BIT)                                                                  \
			opts |= MPPE_OPT_UNKNOWN;                                                              \
		if (ptr[1] || ptr[2])                                                                      \
			opts |= MPPE_OPT_UNKNOWN;                                                              \
		if (ptr[3] & ~MPPE_ALL_BITS)                                                               \
			opts |= MPPE_OPT_UNKNOWN;                                                              \
	} while (/* CONSTCOND */ 0)

/* Shared MPPE padding between MSCHAP and MPPE */
#define SHA1_PAD_SIZE 40

static const u8_t mppe_sha1_pad1[SHA1_PAD_SIZE] = {
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
static const u8_t mppe_sha1_pad2[SHA1_PAD_SIZE] = {
    0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
    0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
    0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2};

/*
 * State for an MPPE (de)compressor.
 */
typedef struct ppp_mppe_state {
	lwip_arc4_context arc4;
	u8_t master_key[MPPE_MAX_KEY_LEN];
	u8_t session_key[MPPE_MAX_KEY_LEN];
	u8_t keylen; /* key length in bytes */
	/* NB: 128-bit == 16, 40-bit == 8!
	 * If we want to support 56-bit, the unit has to change to bits
	 */
	u8_t bits;                 /* MPPE control bits */
	u16_t ccount;              /* 12-bit coherency count (seqno)  */
	u16_t sanity_errors;       /* take down LCP if too many */
	unsigned int stateful : 1; /* stateful mode flag */
	unsigned int discard : 1;  /* stateful mode packet loss flag */
} ppp_mppe_state;

void mppe_set_key(ppp_pcb *pcb, ppp_mppe_state *state, u8_t *key);
void mppe_init(ppp_pcb *pcb, ppp_mppe_state *state, u8_t options);
void mppe_comp_reset(ppp_pcb *pcb, ppp_mppe_state *state);
err_t mppe_compress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb, u16_t protocol);
void mppe_decomp_reset(ppp_pcb *pcb, ppp_mppe_state *state);
err_t mppe_decompress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb);

#ifdef __cplusplus
}
#endif

#endif /* MPPE_H */
#endif /* PPP_SUPPORT && MPPE_SUPPORT */
